Thermostatically controlled cabinet



Feb.'12, 1935. L. A. GEBHARD I 1,991,275

. THERMOSTATICALLY CONTROLLED CABINET Filed Jan. 8, 1930 5 Sheets-Sheet 2.

. INVENTOR. 510m 61. 9066044 A TTORNEY L.A GEBHARD L99L276 THERMOSTATICALLY CONTROLLED CABINET Filed Jan. 8, 1950 5 Sheets-Sheet 3 l u I I l l l I l I I I I l l I m E? I Fbb.12,1935.

Feb. 12,1935. 7 A RD 1,991,276

THERMOSTAIICALLY CONTROLLED CABINET Filed Jan. 8, 1930 5 Sheets-Sheet 4 IN V EN TOR.

10m 61 I BY ATTORNEY Feb: 12, 1935. L. A. GEBHARD THERMOSTATI CALL! CONTROLLED CABINET Filed Jan. 8, 1930 5 Sheets-Sheet 5 INVENTOR ATTORNEY Patented Feb: 12, 1 935.

PATENT OFFICE THERMOSTATICALLY CONTROLLED CABINET Louis A. Gcbhard, Washington, I). 0., asalgnor to Wired Radio, Inc., New York, N. Y., a corporation of Delaware Application January 8, 1930, Serial No. 419,401

3 Claims.

My invention relates to temperature control of electro-mechanically vibratile elements employed in signaling systems.

An object of my invention is to provide a temperature control apparatus employing a great number of electro-mechanically vibratile elements.

Another object of my invention is to provide a constant temperature control apparatus whereby a plurality of electro-mechanically vibratile elements may be selectively associated with an external circuit.

Still another object of my invention is to provide a constant temperature control apparatus containing a large number of electro-mechanically vibratile elements maintained at substantially uniform temperature.

A further object of my invention is to provide a temperature control apparatus containing a large number of electro-mechanically vibratile elements maintained at uniform temperature and whereby the elements may be selectively associated with an external circuit.

' Other and further objects of my invention reside in the provision of certain improved structural features, a better understanding of which can be had from the specification following and from the accompanying drawings, wherein:

Figure 1 shows a top plan view in part section of the temperature control apparatus of my invention; Fig. 2 shows a front view of the apparatus with a portion of the front broken away; Fig. 3 shows a top plan view illustrating the heating element in this portion; Fig. 4 shows a side elevation of the apparatus of my invention illustrating the heater element in this portion; Fig. 5 shows certain structural features of the sides of the container; and Fig.- 6 shows a modification of the assembly arrangement employed in the temperature control apparatus of my invention.

In high frequency transmitters it is necessary to employ a system for maintaining the radiated energy at a substantially constant frequency. The exciter or master oscillator with which the apparatus of my invention is associated has the frequency thereof controlled by an electromechanically vibratile element. It is necessary to accurately control the temperature of the electro-mechanically vibratile element, employed in order to maintain the selected frequency constant. 'Should. a plurality of elements having different frequency characteristics be employed" it is desirable to maintain all of the elements at substantially the same temperature. This usually necessitates providing a large space in in other figures of the accompanying drawings.

the transmitter unit for the apparatus containing thetemperature controlled elements.

A problem other than available space must be considered, namely, that the elements must be maintained at substantially uniform temperature otherwise the change from one element to another will not establish the necessary standard frequency. A third consideration is that the ele ments must be readily accessible for in;erchange of other elements and the elements must be adapted to be readily and easil'yconnected to an external circuit and selectively chosen by the frequency characteristics of the external circuit. The apparatus of my invention presents the foregoing desirable features and advantages as will appear from the specification following:

Fig. 1 is a top plan view in part section showing the apparatus of my invention. The electromechanical vibratile elements 2 are mounted on a framework contained within container 1. A stationary contact member 6 is carried by a con tact arm 7 which is secured to bar8 by means of screw 7a. Bar 8 is supported by an angle 9. Elements 2 have associated contact lugs which engage with clips 19 and 20. Clips 20 are po- 2 sitioned on an annular metallic member 12 by screws 12a. Member 12 is in turn supported by shaft 11 which is of metal. Elements 2 rest upon a-disk 10 which may be of insulating material. Near the periphery of disk 10 contact clips 19 areprovided for retaining the other contact lug of elements 2. The electrical connection to elements 2 is therefore provided by connecting to contacts 23 and shaft 11. Disk 10 may be of metal, in which case clips 19 and contacts 23 would be supported by but suitably insulated from disk 10. V

Disk 10 is supported from shaft 11 by member 12 and is movable therewith. I A second disk 10a is also carried by shaft 11 which disk is similar to disk 10 and carries a plurality of mechanically vibratile elements 2a. Disk 10a and one of the elements 2a is shown in-the broken section of disk 10. Shaft 11 is supported in suitable bearings shown in the figures following, and is rotated 45 by shaft 26 under control of knob 52 to which dial 52a is attached, the details of such mecha nism as necessary for control, being also. shown The revolving framework carrying the elements 2 and 2a and the aaticnflry contact assembly are all positioned with respect to a frameworkcomprising a'lower plate member 16 and upper plate member 15. Rods 17 extend between the lower plate member 16, and the upper plate member 5 15. Inasmuch as Fig. 1 is a section through the cabinet below the upper plate member 15, only the lower plate member 16 is shown although the arrangement of the plate members is clearly shown in Fig. 2.

Container 1 is cube shaped which is satisfactory for most purposes. The ideal shape would be spherical. However, manufacture of this design would not be practicable. The nearest approach is the cubical shaped construction employed in accordance with my invention. All six sides of the cube shaped container are made up of laminated sheets of material. The outermost layer 27 is of suitable insulating material. The second layer 28 is of insulating material upon which the heater wire 29a is wound. Next is a thin layer of mica 29b or other electrical insulating but heat conducting material. This layer is employed primarily to electrically insulate-the heater from the next two layers 31 and 31a which are of metal such as aluminum, and which act as heat distributing layers. A filler layer-29 is provided which substantially surrounds the thin layer of mica 29b and heater wire 29a thus equalizing the thickness of the several layers at any position through the walls. Layer 29 may be made of any suitable heat insulating material. Next is a layer of asbestos 33 or similar material which is adiacent to a layer of copper 33a. Any desired number of alternate layers of asbestos 33 and copper 33a may be provided between the distributing layers 31, 31a and the inside layer 34 of the container which may be of aluminum or other suitable material for lining the interior of the container. The distributing layers 31, 31a

are bulged as shown at 32c providing an open-- ing for a mercury type thermostat 32. To permit access to the mechanically vibratile elements, a door 37 is provided in the front side of container 1. The opening for the door is of special design, the edges being stepped as shown at 36. By recessing the edges in this manner a very efficient heat insulating joint can be had. Leakage of air to the inside of the compartment or vice versa is almost entirely eliminated. Thermometer 40 is provided to indicate the temperature of the inside of the compartment. Thermometer 40 has an upturned portion 41 at right angles to body 40. This permits visual indication of the temperature scale. Thermometer 40 extends through an opening in the front of container l and is positioned adjacent the front by means of clamping screws 42. v

Fig. 2 of the accompanying drawings shows a front view of the temperature control apparatus of my invention. A portion of the front of container 1 is shown cut away showing disks 10 and 10a, upper plate 15 and lower plate 16 in section.

Shaft 11 rests in bearings 13 and 14 provided in plate members 16 and 15, respectively. Like reference characters are employed throughout the drawings. A resilient arm member 21 is carried by collar 21b mounted on shaft 11. Arm 21 carries a semispherical member 21a which engages with detents located in the surface of ring member 22 and as shaft 11 rotates the detents serve as stops to maintain the electrical connectlon to the ring 22. Ring 22 is secured in position with respect to member 15 by means of screws 22a by which an electrical connection to screw 22a may be provided in any suitable manner. Bar 8 may be secured to plate members 15 and why means of angle members 9 and screws 8a. Bevel gears 25 interconnect with shaft 11 element, there are and with shaft 26. Shaft 26 extends at right angles to shaft 11 and protrudes through the front side of container 1. Shaft 26 may be entirely of suitable insulating material thepurpose of which is to prevent any pronounced transfer of heat between the inside and outside of container 1, or the shaft 26 may be broken by a suitable insulating coupling at the position where the shaft 26 passes through the walls of the cabinet contacts 23 and 24 in engagement with brushes 6. Disks l0 and 10a are shown in section comprising a carrier for elements 2 and 2a, respectively. As shown, elements 2 and 2a are piezo electric crystals contained in individual holders which are removable. Clips 19 and 20 connect to the two contact lugs carried by the holders and establish electrical connection to the crystal elements.

A brush 21c mounted on collar 21b extends radially opposite arm 21 to form a movable electrical contact with ring 22. Part of the surface of ring 22 contains the detents for receiving the member 21a while the remainder of the surface of the ring 22 is employed for providing contact with brush 21c.

While piezo electric crystal elements have been referred to, it is obvious that other elements such as magnetostriction rods may be employed. The necessity for maintaining the temperature of magnetostriction rods at a constant value, is as important as maintaining constant the temperature of piezo electric elements. From the outside of container 1 the selection of different elements may be controlled by dial and knob 52 vhich is carried on shaft 26. also indicates the element which is connected to Dial and knob 52 the external circuit at each adjustment. With a permanent selection of elements as in a transmitting system operating on certain frequencies, dial 52 may be calibrated in kilocycles. Door 37. is shown in section. The edges of door 3'? are recessed as shown in Fig. l at 36. Hinges 38 are provided at the left of the door and a latch is provided at the right. This latch is not shown in the accompanying drawings but is of suitable design to force door 37 to form a very close fit with the recessed edges of the front wall of container 1. Where the hinged door carries a heater provided suitable flexible con nectors Gil-61 between the heating element in the cabinet walls and the terminals 62-63 of the heating element carried by the hinged door for completing the electrical circuits. The outer most layer 27 of suitable insulating material is here shown in section, exposing layer 28 upon which the heater element is wound. The heater wire is wound in notches 28a disposed in the opposite ends of layer 28 and extends across the layer as illustrated. The top and bottom turns of the heater wire are secured to the notches 28a as shown at 29a, while the principal portions of the heater wire are disposed on the inner side of layer 28. Between layer 28 and the distributing layers ofmetal, previously referred to, a layer 29 of suitable heat conducting and electrical insulating material is provided.

Thermometer 40 is shown in section; a clamping member 42 securing the body of the thermometer in the proper position and the graduated temperature scale or upstanding portion 41 in a vertical position. The body of thermometer 40 extends through the front panel of container 1. The upstanding portion 41 is calibrated and indicates the temperature inside the container. The mercury type thermostat 32, also 'by providing an opening for the body of the thermostat.

The control portion or stem extends through bushing 32!: which is threaded into the insulating layers on the top side of con- 1 tainer 1. Lower plate member 16 forming part of the unit framework is elevated from the bottom of container 1 by members 35. Screws 51 are provided .to secure the heat insulating layer 2'! to the other layers of the container. Screws 50 extend from layer 28 through to layer 34. This feature will be referred to later in connection with the figures to follow.

Fig. 3 of the accompanying drawings shows a top plan view of the temperature control apparatus of my invention. In this illustration the outside or upper layer 2'! of heat insulating material is shown in section thus exposing the heater element. As inthe foregoing illustrations, the heater element is wound in notches 28a provided in layer 28. Screw holes 50a are shown through which the screws51 pass when the outermost panel 27 is in place. By removing the four screws indicated, access is had tothe heater ele- .ment for adjustment, repair or replacement.

This feature is: very desirable since it is often times necessary to adjust the lengthof the heater wire employed toprovide equality of temperature in all sides of the container 1. A and B indicate binding posts which are employed in a modification of my invention. The heater element is separated near the binding posts A and B to avoid any short circuit of the heater elements. Dial.52 is shown carried on shaft 26 at the front of the container. By means of dial 52 selection of the desired piezo electric element is made possible as aforementioned in connection with Fig. 2. The upstanding stem 41 of mercury type thermometer 40 is positioned to the front of container 1 by means of clamping members 42. This thermometer indicates the temperature of the inside of the container. Mercury type thermostat 32 illustrated in Figs. 1, 2 and 4 is secured by bushing 32b in the wall of the cabinet structure. The thermostat socket is constructed by causing a bulge in the distributing layers 31 and 31a which receives the thermostat as has been described heretofore. I

Fig. 4 of the drawings shows a side elevation of the temperature controlled apparatus of my invention. Corresponding reference characters are employed in all of the figures.

In this illustration, as inthat of Fig. 3, the outermost layer 27 is removed exposing the layer 28 upon which the heater element is wound. The constructionis similar to that shown in the fore going illustrations previously referred to. The heater element is separated as shown because of the bulge in the distributing layers for the thermostat 32. Shaft 26 carrying dial 52 is shown extending through the front side of 'container 1. Thermometer 40 is shown, the calibrated portion or stem 41' extending parallel to the front side of container 1 retained in this position by means of clamping members 42.-

Fig. 5 shows a section of the wall of container 1 1 and illustrates the method of mounting different members on the container. The layers as previously mentioned are insulating layers 27 and 28, heat conducting andelectrical insulating layer 29, heat distributing layers 31 and 31a, alternate layers of asbestos or the like'and suitable metal such as copper 33 and 33a respectively and the inside lining 34 of suitable metal such as aluminum. The essential feature shown in this illustration is that no screws extend through the entire wall of the container. Such screws if extended through all of the layers would offer a path of relatively high temperature conductivity. For this reasonthe screws are arranged in a manner somewhat as shown, wherein screw 51 extends part way through the wall, namely through the layers 27, 28, 29. and threaded into the distributing layers 31, 31a.

'I'hemember 5B is secured by a separate screw 50 which extends through layers 28, 29, 31, 31a, 33, 33a and 34. A countersunk screw as shown may be employed in the latter instance. Where it is not desired to mount a member 58 on the inside of the container, screw 50 may be threaded into the innermost layer 34. By fastening the several layers together in this manner, any apparatus desired may be mounted directly upon metallic layer 34; The screws may be distributed on the several walls of container 1 as desired depending upon the rigidity sought.

Fig. 6 of the accompanying drawings shows a modification of the temperature controlled apparatus of my invention. The illustration shows a sectional view taken through the side wall of the container showing particularly the top and right side of the container. It is sometimes desired to remove the entire rotatable frame-'- work which carries the mechanically vibratile; elements. As heretofore mentioned, the elements associated with the adjusting. mechanism and contact members are mounted on a framework consisting of an upper and lower plate member and supported by rod members extending vertically as shown in,Figs. l and 2. The upper plate member 15 is here shown carrying contact member 43 supported by upstanding members 55.

Contact member 43 consists of two laminated An insulating body 46a surrounds the metallic body 46, thereby electrically insulating the same,

from the metallic distributing layers. An elec- -trical connection is established between terminal 43a of contact 43 to the stationary contacts or supporting bar 8 shown in Fig; 2. By referring to Fig. 2 it may be seen how such connection can be provided by connection to screw 8a. 7 An arrangement similar to that shown in Fig. 6 is also provided for establishing electrical connection to the other side of the mechanically vibratile element, which as heretofore described is provided for metallic annular shaped member 22. In the latter connecting arrangement a contact member similarto contact 43 is electrically connected to annular shaped ring 22 or 'to the mounting screw 22a which holds the same to upper plate member 15. The duplication of the arrangement shown in Fig. 6 is not shown but the terminal leading therefrom is indicated by binding post A, shown in Fig. 3. This contact arrangement is provided whereby it is possible, by removing the front wall of container 1, to remove the entire framework carrying the vibratile elements thereby permitting access to the unit in its entirety for repair, replacement and the like.

of the operation and certain advantageous features will appear. The elements 2 on the upper platform 10 and the elements 2a on the lower platform 10a are arranged to be connected to the external circuit in alternate order. This may be accomplished by having the elements 20 positioned offset as shown in Fig. 1 or the equivalent, the contact members offset in like manner;

The stationary contact members 6 carried by bar 8 may be suitably arranged to connect to elements 2 and 2a in alternate order when ele ments 2 and 2a are positioned immediately under each other instead of the offset positioning as shown in Fig. 1. Any number of disks similar to disks 10 and 10a may be employed arranged one over the other as shown. The elements or connection to the elements may be from first one disk and then the next in successive order which may be effected by placing the rotating contacts for the elements in echelonic formation with respect to the diiferent disks or the stationary contacts may be arranged in such a manner if it is desired to place the elements in line one over the other on the respective disks. The disks should be of sufficient number or proportionally spaced on shaft 11 to occupy the area of a cube as nearly as possible. four disks of diameter d are employed the vertical dimension occupied by all the disks should be (1 and the separation between the disks divided accordingly.

The various layers constituting the sides of container 1 are interleaved at the corners as shown in Fig. 1 of the accompanying drawings. The heater elements in the six sides are con nected in 'series to permit the same current to pass through each element. Minor irregularlties in the heating can be controlled by adjustingthe length of the wire constituting the heater element in each of the sides. The container 1 in its entirety is mounted on the front panel of the radio transmitter or apparatus.

A door should be provided in the front panel of the transmitter corresponding to the position of door 37 by means of which access to the mechanically vibratile elements may be had. A suitable window should also be provided in the front panel to permit sighting thermometer 41. Thermostat 32 is located adjacent the heater element provided in container 1 and connected with a suitable source of electrical energy for controlling the current to the heater. The framework supporting the rotating platforms is accured to the front panel and may be drawn out horizontally in the process of disassembly which disengages the contacts 44 and 43 permitting withdrawal of the equipment in order that repairs or mechanical adjustment may be made to the mechanism. Screws 80 are provided through the laminations 28, 29, 31, 31a, 33, 33a and 34 for binding the front group of layers to enable the front section to be removed or inserted as a unit. Access to any one of the crystals is readily obtained by rotating the platforms to bring the desired crystal to a position at the front of the cabinet from which it may be inserted or removed.

The apparatus of my invention may be mounted with respect to a panel of a radio transmitter as indicated in Figs. 2 and 3 at 64 with a suitable window 65 cut in the panel64 to permit sighting the scale ofthe thermometer 41 therethrough. Shaft 26 projects through the front of panel 64, the knob 52 and dial being secured to the end of shaft 26. The calibrations on the dial are registered with a calibrationon panel 64 to enable the apparatus to be shifted to the desired frequency.

Many modifications of my invention are possible and it is to be understood that the embodiments of my invention are not to be restricted by the foregoing specification or by the accompanying drawings but that changes may be made within the scope of the appended claims without departing from the spirit of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is as follows:

1. Apparatus of the class described, comprising a cabinet structure, a plurality of layers of respectively heat conductive and heat insulating material comprising the walls of said cabinet structure, a heating element disposed between certain of said layers, a thermostat imbedded between said heat conductivelayers for controlling the heat generated by 'said heating element, means for firmly binding together said wall layers, the individual components of said means extending through fewer than the full number of said layers, and means for disposing objects symmetrically within said cabinet structure so as to be uniformly heated.

2. A thermostatically controlled cabinet having laminated walls the interior portions of which are formed of heat conductive material and the exterior portions of which are formed of heat insulating material, electrical heaters disposed between certain of the laminations of said wall and retained in position by stretching the same back and forth over the notched edges of one layer of said laminationsso as to distribute their heat evenly, a thermostat for controlling the heat generated by said electrical heaters and a plurality of objects symmetrically disposed within said cabinet so as to be maintained at a uniform temperature.

3., A thermostatically controlled cabinet having laminated walls, certain of the laminations of which are of insulating material, certain of the same of heat conductive material and others of which are notched, by stringing the same from notch to notch of said laminations and disposed in substantially equi-distant courses over a major portion of the area thereof, the relation between said heating wire and said heat conductive laminations being such as to distribute the heat evenly over the interior walls of said cabinet.

LOUIS A. GEBHARD.

a heating wire held in place 

